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1、The Linux-SRT Integrated Multimedia Operating System: Bringing QoS To The Desktop,Speaker: Yan-Pai Chen,Stephen Childs and David Ingram University of Cambridge,Outline,Introduction Background Scheduler Implementation Evaluation Conclusion,Introduction,Soft real-time (SRT) requirement for application
2、s on the PC Drawback of existing time-sharing designs cant predictably provide a specific proportion of system resources CPU scheduling alone isnt enough contention for access to other resource can render CPU reservation worthless,Introduction,Main idea Close integration between system components is
3、 necessary Scheduling policies should be respected throughout the system,Background,Standard Linux scheduling CPU scheduling Dynamic Static Disk scheduling Provide no way for users to influence the priority of disk requests,Scheduler Implementation,Linux-SRT features Standard Linux For time-sharing
4、processes: SCHED_OTHER For RT processes: SCHED_RR, SCHED_FIFO Linux-SRT adds SCHED_QOS SCHED_PAUSE SCHED_IDLE,Scheduler Implementation,Reserve the unit of resource allocation, and encapsulates scheduling parameters,Scheduler Implementation,CPU scheduling PrecedenceSCHED_QOS SCHED_RR SCHED_FIFO SCHED
5、_OTHER SCHED_IDLE SCHED_PAUSE Fallback policy when a tasks resource usage exceeds its limit, it is scheduled according to a fallback policy Sample scheduling policies,Scheduler Implementation,Disk scheduling The same as the CPU scheduling Disk requests are tagged with PIDs Multiple device support Ea
6、ch scheduled device has its own list of reserves Schedulers of devices are responsible for their own accounting, scheduling and policing,Evaluation,CPU scheduler effectiveness,Evaluation,Disk scheduler effectiveness,Conclusion,Existing applications can benefit from QoS without being modified Support QoS for multiple devices Future work Adaptively Support multi-processor system and network devices,
